Therapeutic use of tetrasodium ethylenediaminetetraacetic acid solution for treatment of subcutaneous ureteral bypass device mineralization in cats

Medical and Surgical Management of Ureteral Obstructions

Many patients with ureteral obstructions are critically ill at the time of diagnosis, especially if there is dysfunction of the contralateral kidney. They may present with varying severities of uremia and acute kidney injury as well as systemic inflammation and sepsis secondary to infection. Medical management, which may consist of rehydration and restoration of intravascular volume with intravenous fluid therapy, osmotic diuresis, ureteral muscle relaxation, and antimicrobials for infection, is important in ureteral obstruction patients. Unstable patients may require more emergent intervention to relive the obstruction and address the life-threatening sequelae to acute kidney injury.

Assessing Ureteral Patency by Fluoroscopy and Ultrasonography After Subcutaneous Ureteral Bypass Device Placement for the Treatment of Benign Ureteral Obstruction in Cats

BACKGROUND

Limited information on the patency of native ureters after subcutaneous ureteral bypass (SUB) device placement is available.

OBJECTIVE

Evaluate the patency of native ureters in cats treated with SUB device placement for benign ureteral obstruction.

ANIMALS

Cats with SUB presented for routine evaluation.

METHODS

Routine ultrasound-guided SUB irrigations were performed, focusing on ureteral irrigation in the trigone and proximal urethra. Cats with obstructed nephrostomy catheters or subcutaneous ports were excluded. Fluoroscopic-guided SUB irrigations with iodinated contrast then were used to assess patency. Ureters were deemed patent if contrast filled the lumen evenly along their length, and obstructed if the contrast column was interrupted on consecutive images. Intraoperative fluoroscopy was reviewed to confirm the cause and location of the obstructions.

RESULTS

Overall, 18 cats (18 SUBs; 10 unilateral, 8 bilateral) were included. The causes of obstruction were ureteroliths (23 ureters) and presumed stricture (3 ureters). A trigonal irrigation was visible in 14/18 cats (77%; 95% confidence interval [CI]: 54.8%-91.0%); the patent side in bilateral SUBs could not be differentiated. Three ureters were excluded (nondiagnostic study, n = 1; obstructed nephrostomy, n = 2). Of the remaining 23 ureters, 19 (82.6%; 95% CI: 62.9%-93.0%) were patent: 16/20 patent ureters were obstructed with ureteroliths (80%; 95% CI: 58.4%-91.9%) and 3/3 with presumed stricture (100%; 95% CI: 43.9%-100%). Ureteral irrigations at the trigone were associated with patency.

CONCLUSIONS

A high patency rate of native ureters after SUB placement was observed. Ureteral irrigations at the trigone reliably indicate patency. Supraphysiologic SUB irrigations may result in underdiagnosed persistent partial obstructions.

Enhanced popcorning using polyanionic chelating solutions as irrigation

Poly-anionic compounds can chelate divalent cations and dissolve calcium oxalate stone. Our objective was to assess how much concurrent irrigation with poly-anionic chelating solutions during non-contact laser lithotripsy or popcorning could improve stone ablation rate. A popcorning model was created by lowering a ureteroscope with thulium fiber laser into a test tube calyx. Begostones of matching size and mass were placed in the test tube and treated with the laser while irrigating with different iso-osmolar poly-anionic solutions. We compared 0.9% sodium chloride (NaCl), sodium citrate, sodium hexa-metaphosphate, and sodium ethylenediaminetetraacetate (EDTA) solutions. After treatment, residual stones were passed through a 1 mm sieve, and remaining fragments greater than 1 mm were weighed as remaining stone mass. Average remaining stone mass after lithotripsy with NaCl irrigation was 27.8% (± 10.0%). The average remaining stone mass after lithotripsy with hexa-metaphosphate, sodium citrate, and EDTA irrigation was 28.9% (± 13.4%), 17.5% (± 10.5%), and 9.8% (± 5.7%) respectively. Compared with NaCl, there was a 37% reduction in remaining stone mass when using citrate (p = 0.008) and a 64.7% reduction when using EDTA irrigation during lithotripsy (p < 0.001). Concurrent irrigation with citrate or EDTA solutions synergistically enhances the efficacy laser lithotripsy in this in vitro popcorning model. This may lead to tangible improvements in endoscopic stone removal outcomes; however, the effectiveness on different stone types and safety during short duration lithotripsy should be further investigated.

Feline ureteral rupture with para-ureteral urinomas following blunt trauma: clinical presentation and long-term outcome after treatment by urinary diversion for five cases from 2012 to 2019

CASE HISTORY

Medical records were reviewed for cats that underwent surgical treatment of traumatic ureteral rupture (TUR) using urinary diversion procedures between 2012 and 2019.

CLINICAL FINDINGS AND TREATMENT

Five cats had presented with injuries associated with road traffic accidents. These included three cats with abdominal hernias that required surgical management. At a median of 15 days after the accident, cats represented with lethargy, the presence of an abdominal mass or with lower urinary tract symptoms and in all cats contrast diagnostic imaging showed proximal unilateral TUR with associated para-ureteral urinoma. Four cats received subcutaneous ureteral bypass (SUB) device placement and one had ureteral anastomosis over a stent. Unilateral cyst-like retroperitoneal fluid consistent with para-ureteral urinoma was observed in all cats and a diffuse retroperitoneal haematoma was noticed in four cats. No immediate major complications occurred, and all cats had post-operative serum creatinine concentration within the reference interval. The cat that had received a ureteral stent subsequently required placement of a SUB following stent encrustation 15 months after surgery. Median follow-up time was 34 (min 28, max 58) months and renal function was normal in all cats at the last follow-up.

CLINICAL RELEVANCE

Urinary diversion procedures provided long-term stable renal function following proximal TUR in these five cats. Delayed, subtle non-specific clinical signs subsequent to high-energy blunt trauma causing abdominal hernia and associated diffuse retroperitoneal haematoma, should raise suspicion of TUR.

ABBREVIATIONS

AFAST: Abdominal focused assessment with sonography for trauma; SUB: Subcutaneous ureteral bypass; TUR: Traumatic ureteral rupture.

Use of tetrasodium EDTA acid for the treatment of intraluminal obstruction of subcutaneous ureteral bypass devices

OBJECTIVES

The aim of this study was to evaluate the efficacy and tolerability of a 4% tetrasodium EDTA (tEDTA) infusion protocol in the subcutaneous ureteral bypass (SUB) devices of cats with intraluminal obstruction at a veterinary teaching hospital between July 2017 and April 2020.

METHODS

This was a retrospective controlled study. Cats with an obstructed SUB device underwent a 4% tEDTA infusion protocol. Obstruction of the device was diagnosed based on renal pelvic dilation, dilatation of the ureter, mineralized material within the device (cystostomy or nephrostomy catheters) seen on ultrasound, the absence of visible bubbles within the renal pelvis and/or urinary bladder following ultrasound-guided flushing of the device with saline.

RESULTS

A total of 16 tEDTA infusion protocols were performed in 14 cats. The infusion protocol was considered successful in 11/16 SUB devices (68.8%). Six devices (n = 6/11; 54.5%) had recurrence of obstruction with a median time of 87 days. One or more episodes of self-limiting pollakiuria and/or hematuria following infusion was seen in eight patients (n = 8/14; 57.1%).

CONCLUSIONS AND RELEVANCE

Infusions of 4% tEDTA successfully relieved intraluminal obstruction in patients with occluded SUB devices; however, the recurrence of obstruction was common. Additional studies evaluating case selection and optimal protocols are warranted.

Risk factors and clinical relevance of positive urine cultures in cats with subcutaneous ureteral bypass

Background

The objective of the study was to report the incidence and risk factors associated with positive urine bacterial cultures as well as long-term outcome in cats with subcutaneous ureteral bypass (SUB) devices.

Results

Medical records of cats that underwent SUB device placement were retrospectively reviewed. Signalment of the cat, laterality of the ureteral obstruction, surgery, anesthesia and hospitalization duration, bacterial culture results and follow-up data were retrieved.

Thirty-two cats met the inclusion criteria. Four cats (12.5%) had a positive intraoperative culture, with two of them being treated successfully. Ten cats out of 28 (35.7%) were documented with a positive urine culture during follow-up period, with a median time between discharge and identification of the first positive urine culture of 159 days (range 8–703 days). Bacteriuria resolved in 60% of cats (6/10). Escherichia coli was the most common organism, isolated in 4 out of 10 postoperative urine cultures. Overall, subclinical bacteriura was documented for 6 of 32 (18.8%) cats and 5 of 32 (15.6%) cats displayed clinicals signs suggestive of persistent UTI. One cat had subclinical bacteriuria. Three cats died during the follow-up period.

There was a significant difference between negative and positive urine bacterial culture groups in median hospitalization duration (5 days versus 6 days, P = 0.022) and in median body condition score (5/9 versus 4/9, P = 0.03). Cats with a longer hospital stay and with a lower body condition score were more likely to have a positive urine culture during follow-up period.

Conclusions

SUB device placement surgery is associated with complications such as chronic bacteriuria. Bacteriuria in our study resolved with appropriate antibiotic treatment in more than half of cats. Risk factors identified for positive urine culture were a longer hospitalization duration and a decreased body condition score.

Intestinal perforation involving the Dacron cuff of nephrostomy tubes following subcutaneous ureteral bypass system implantation for ureteral obstructions in two cats

CASE SUMMARY

This case report describes two cats that had subcutaneous ureteral bypass (SUB) systems implanted and subsequently developed duodenal perforations and septic peritonitis associated with the Dacron cuff of the nephrostomy tube. One cat recovered following surgical explantation of the SUB system with intestinal resection and anastomosis of the perforated small intestine, and - at the time of writing - is still alive. The other cat was humanely euthanased intraoperatively at the owner's request owing to its perceived prognosis.

RELEVANCE AND NOVEL INFORMATION

To our knowledge this is the first time this complication has been reported following SUB device placement.

Outcome of SUB placement for the treatment of benign ureteral obstruction in dogs: nine dogs and 12 renal units (2013 to 2017)

OBJECTIVES

To describe a group of dogs with benign ureteral obstruction(s) treated by subcutaneous ureteral bypass and report the intra-operative, peri-operative, short- and long-term outcomes.

MATERIALS AND METHODS

Review of medical records of dogs that underwent subcutaneous ureteral bypass.

RESULTS

Nine dogs (12 renal units) were included. Causes of obstruction included: ureterolithiasis (n=9) extraluminal compression (n=2), and stricture (n=1). Eleven of 12 ureters had a previously placed stent and required subcutaneous ureteral bypass for: recurrent stricture (n=4), diffuse ureteritis (n=4) or stent migration (n=3). Placement was successful in all renal units and there were no peri-operative or procedure-related deaths. Median hospitalisation time was 3 days. The median creatinine values pre-operatively and 3 month post-operatively were 186 and 106 μmol/L, respectively. No dog had worsening azotaemia in the short-term. The most common long-term complication was mineralisation of six devices, of which four required exchange. All dogs that were infected post-operatively (n=5) had a history of at least one urinary tract infection pre-operatively. One of the nine dogs had a chronic post-operative urinary tract infection and had been chronically infected before placing the bypass. The median survival time was >774 days, with five of nine dogs alive at the time of publication.

CLINICAL SIGNIFICANCE

Placement of a subcutaneous ureteral bypass was an effective short-term treatment option for benign ureteral obstructions in dogs but there was a high rate of device mineralisation.

Infection and extrusion of a subcutaneous access port in a cat: a long-term postoperative complication of a subcutaneous ureteral bypass device

Case summary

A 5-year-old domestic shorthair neutered female cat was presented for a wound in the region of the subcutaneous ureteral bypass shunting port with externalisation of the device, 2 years after its initial positioning. The cat had had positive urine bacterial cultures over the previous year and a half without any clinical signs of urinary tract infection. Bacterial cultures of urine and the wound revealed the same bacteria, suggesting a complication caused by infected urine from the implanted system. The wound was successfully treated with surgery and at the time of writing, 3 months later, the cat is healthy with no evidence of recurrence.

Relevance and novel information

To our knowledge, this is the first report of a subcutaneous ureteral bypass shunting port extrusion as a long-term major complication of the bacterial infection of the device.

Therapeutic use of tetrasodium ethylenediaminetetraacetic acid solution for treatment of subcutaneous ureteral bypass device mineralization in cats

Background

Subcutaneous ureteral bypass (SUB) device placement is an increasingly popular treatment option for decompression of ureteral obstruction in cats. Mineralization occlusion of the device occurs in a minority of cases but is the most common complication.

Objective

To evaluate a 2% tetrasodium ethylenediaminetetraacetic acid (tEDTA) solution for treatment of mineralization occlusion in cats with SUBs.

Animals

Six client‐owned cats (8 obstructed devices).

Methods

Case series. Each cat was found to have device occlusion based on a combination of ultrasound examination, SUB irrigation, and failure to identify another cause of device obstruction. Each SUB was drained, irrigated using sterile saline, and infused with 1‐2 mL of 2% tEDTA solution. Success was defined as normalization of flow during subsequent ultrasound visualization while irrigating. The volume and frequency of tEDTA instillations, time to achieve device patency, follow‐up biochemical and ultrasound findings, and future reobstruction events were recorded.

Results

Resolution of mineralization was documented in all 8 SUBs. Reobstruction events occurred in 2 cats, all of which resolved after additional tEDTA infusions, but 1 cat ultimately required device exchange at 356 days from the first tEDTA infusion. In 1 cat, a single infusion was prematurely discontinued because of persistent pelvic dilatation after 1.25 mL of tEDTA had been instilled. No complications were observed.

Conclusions and Clinical Importance

Tetrasodium EDTA infusions can be safely considered as a treatment option for mineralized SUB devices in cats. This solution was easily infused, well tolerated, and avoided the need for SUB device exchange in the majority of cats in which it was used.